Update UniFile

Which has more correct nullability for some methods and case insensitivity for listFiles where possible.

app/src/main/java/eu/kanade/tachiyomi/data/backup/BackupCreateJob.kt

@@ -58,7 +58,7 @@ class BackupCreateJob(private val context: Context, workerParams: WorkerParamete
             if (isAutoBackup) {
                 backupPreferences.lastAutoBackupTimestamp().set(Date().time)
             } else {
-                notifier.showBackupComplete(UniFile.fromUri(context, location.toUri()))
+                notifier.showBackupComplete(UniFile.fromUri(context, location.toUri())!!)
             }
             Result.success()
         } catch (e: Exception) {

app/src/main/java/eu/kanade/tachiyomi/data/backup/BackupCreator.kt

@@ -95,14 +95,14 @@ class BackupCreator(
                     val dir = UniFile.fromUri(context, uri)
 
                     // Delete older backups
-                    dir.listFiles { _, filename -> Backup.filenameRegex.matches(filename) }
+                    dir?.listFiles { _, filename -> Backup.filenameRegex.matches(filename) }
                         .orEmpty()
                         .sortedByDescending { it.name }
                         .drop(MAX_AUTO_BACKUPS - 1)
                         .forEach { it.delete() }
 
                     // Create new file to place backup
-                    dir.createFile(Backup.getFilename())
+                    dir?.createFile(Backup.getFilename())
                 } else {
                     UniFile.fromUri(context, uri)
                 }